On December 21, Jupiter and Saturn will get so close in the sky that they will almost appear to merge with one another. Such a close conjunction between the two has not occurred under a dark sky for some 800 years.
This December, Jupiter and Saturn will put on a show for skygazers that hasn’t been seen in roughly 800 years. Astronomers are calling it the Great Conjunction of 2020. On December 21 — coincidentally the winter solstice — the two largest planets in our solar system will appear to almost merge in Earth’s night sky.
During the event, Jupiter and Saturn will sit just 0.1 degrees apart, or a mere one-fifth the width of the Moon. The sight will likely leave many casual observers wondering “What are those large, bright objects so close together in the sky?”
In fact, Jupiter and Saturn will be so close that you will be able to fit them both in the same telescopic field of view. That’s an incredibly rare occurrence. The last time Jupiter and Saturn were this close together away from the Sun was in 1226 A.D., at a time when Genghis Khan was conquering large swaths of Asia, and Europe was still generations away from the Renaissance.
Humanity won’t have to wait quite as long to see the solar system’s two largest planets repeat this month’s performance, though. Another Great Conjunction will occur in 2080. Of course, many of us alive today won’t be around then, so it would be wise to soak in this show while you can.
Jupiter and Saturn conjunction 2020
We don’t have to worry about that this time. Throughout the month, the gas giants will be hard to miss. Jupiter shines brighter than any star in the sky at magnitude -2.0, while Saturn is dimmer at magnitude 0.6 — though the Ringed Planet is still quite bright.
So, you certainly won’t need binoculars or a telescope to see the Great Conjunction of 2020. But if you do have observing equipment, you’ll be able to zoom in and watch the dance of Jupiter’s four moons — Europa, Io, Callisto and Ganymede.
Then, without moving the telescope, you can slightly shift your gaze to Saturn and its magnificent rings. Despite the significant size difference between the planets, Saturn’s massive rings mean the two worlds both appear to have about the same diameter when viewed through a telescope.
As the conjunction reaches its climax on December 21, scopes located in the Eastern United States will be able to catch Ganymede as it transits Jupiter for three and a half hours starting at 7:04 P.M. EST. Meanwhile, telescopic observers on the West Coast will see Ganymede’s shadow hovering over Jupiter’s cloud tops by 9:40 P.M. EST.
You can watch a livestream of the Great Conjunction of 2020 below, courtesy of Lowell Observatory. Beginning at 7 P.M. EST on December 21, Lowell astronomers and educators will share spectacular live views of Jupiter and Saturn through observatory telescopes while discussing the nature of conjunctions.